JPS61283720A - Suction device for diesel engine - Google Patents

Abstract

PURPOSE:To improve the operation of an engine so better, by operating it even in a case other than at the time of starting excepting acceleration, in case of the engine that installs an on-off valve in a suction pipe of a Diesel engine and closes it at the time of starting, while supplies bypass air to the downstream of this on-off valve when the suction valve opens and its pressure is more than the specified suction pressure. CONSTITUTION:An on-off valve 7 is installed in a suction pipe 6a of a Diesel engine, and a control circuit 25 opens or closes a valve 24 by various driving parameters 26-29 of the engine, then the on-off valve 7 is opened or closed by operation of an actuator 21. A passage 6b, which inhales air by bypassing the on-off valve 7, is installed in the downstream of the on-off valve 7, in the midway in this passage, there is provided with a suction operating valve 10, and when the on-off valve 7 is closed and the specified suction pressure is produced as a suction valve 4 opens, the suction pressure operating valve suddenly opens, performing quick suction into a cylinder 3, thereby causing a temperature rise by adiabatic compression. The on-off valve 7 is operated not only at starting but also in an optional engine driving state, but is not closed at acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake device that increases intake air temperature by adiabatic compression in order to promote starting of a diesel engine and improve emissions.

(i) Previous technology As shown in Japanese Utility Model Application Publication No. 59-107936, in order to improve ignitability when starting a diesel engine, intake air supplied to the combustion chamber is adiabatically compressed to increase the intake air temperature. An intake @ position (starting promotion device N) is known. This device has an on-off valve in the intake passage that opens during the intake stroke. Specifically, an intake throttle valve is provided in the main intake passage, and an on-off valve is provided in the bypass intake passage that bypasses the intake throttle valve. During low-load operation from startup to @mechanism, with the main intake passage throttled by the intake throttle valve, the above-mentioned on-off valve is opened during the intake stroke by the valve mechanism or pressure-responsive IFLr11 valve, etc. I try to let them do it. The operation of the on-off valve restricts the intake air into the combustion chamber until the middle of the intake stroke, and rapidly introduces the intake air into the combustion chamber from the middle of the intake stroke to perform adiabatic compression. According to this device, compared to the case where intake air is heated by an air heater, a large amount of energy is not consumed as electric power, and moreover, the intake air temperature can be efficiently raised in the combustion chamber.

By the way, in the conventional device described above, the on-off valve is operated only during the startup warm-up operation to promote startup, but even during normal operation after the first EA engine, white smoke and non-smoking may occur in the exhaust if the combustion temperature is low. Since HC and GO, which are combustion components, are more likely to be generated, increasing the combustion temperature by utilizing adiabatic compression by the operation of the on-off valve will be effective in reducing HC, etc. in the exhaust gas. When the on-off valve 10 is operated in this way, the intake air intake may be regulated and the charging amount may decrease to some extent, but during normal operation of the diesel engine,
Since the engine is in an operating state where the excess air ratio is inherently large, there is no shortage of intake air, and combustion is performed well. However, when accelerating, a large amount of intake air is required as the fuel is increased, and if insufficient intake air occurs, smoke is likely to occur due to over-rich fuel, and the output will decrease, so the amount of filling should be increased as much as possible. There is a request to do so.

(Objective of the Invention) In view of these circumstances, the present invention uses adiabatic compression of intake air to reduce white smoke, HC, etc. in exhaust during steady operation, and also prevents smoke from occurring during acceleration. The present invention provides an intake device for a diesel engine that can improve acceleration performance.

(Structure of the Invention) The present invention provides an on-off valve in the intake passage, closes the on-off valve until the middle of the intake stroke to restrict the introduction of intake air into the combustion chamber, and opens the on-off valve during the intake stroke. In an intake system for a diesel engine equipped with an intake air introduction regulating device that rapidly introduces intake air into a combustion chamber to perform adiabatic compression, an acceleration detection means for detecting an acceleration state of the engine;
A control means is provided for controlling the intake air introduction restriction device in a direction to release the restriction on intake air introduction caused by the operation of the opening/closing valve during acceleration according to the output of the acceleration detection means.

In other words, during steady operation where there is no problem even if the filling amount decreases to some extent, the on-off valve is activated to restrict the intake air intake so that adiabatic compression of the intake air is performed, but during acceleration the intake air intake restriction is released. It is designed to ensure fullness by controlling the direction.

(Example) 1 to 3 show a first embodiment of the present invention.

In these figures, 1 is each cylinder of a diesel engine, and a combustion chamber 3 is located above a piston 2 inside the cylinder.
An intake boat 5 having an intake valve 4 and an exhaust boat (not shown) having an exhaust valve open into the combustion chamber 3.

An on-off valve 1 is provided in the intake passage 6 communicating with the intake boat 5.
0 restricts the introduction of intake air into the combustion chamber 3 until the middle of the intake stroke, and suddenly introduces the intake air into the combustion chamber 3 from the middle of the intake stroke to perform adiabatic compression. In this embodiment, the intake passage 6 is formed separately for each cylinder 1, and includes a main intake passage 6a and an R1 intake passage 6b whose downstream end opens into the main intake passage 6a. An automatic valve type in which an intake throttle valve 7 is provided upstream from the auxiliary intake passage 6b position of 6a, and opens in the middle of the intake stroke in response to pressure changes when the main intake passage 6a is throttled by the intake throttle valve 7. An on-off valve 10 is provided in the sub-intake passage 6b.

The main intake passage 6a and the auxiliary intake passage 6b are connected to an air cleaner (not shown) via surge tanks 8 and 9, respectively.

The on-off valve 10 is arranged at the opening of the auxiliary intake passage 6b to the surge tank 9, and includes a valve body 13 provided in the valve chamber 11 and abutting the valve seat 12 from the upstream side.
a diaphragm 15 connected to via a connecting shaft 14;
Two chambers 16 separated by this diaphragm 15.
17, and a return spring 18 which is provided in one of the chambers 16 and biases the valve body 13 in the direction of the valve. The one chamber 16 communicates with the auxiliary intake passage 6b downstream of the valve body 13 through a communication hole 19 passing through the valve body 13, the connecting shaft 14, and the diaphragm 15, and the other chamber 1
7 communicates with a surge tank 9 and is maintained at approximately atmospheric pressure. According to this structure, when negative pressure is generated in the auxiliary intake passage 6b downstream of the valve body 13, the negative pressure is transferred to the one chamber 1.
6 and due to the pressure difference between the two chambers 16 and 17, the valve body 13
While the force in the opening direction acts on the diaphragm 15, the pressure on the valve body 13 itself and the return spring 18
The spring force becomes a resistance force, and when the valve body 13 is opened, the negative pressure acting on the valve body 13 itself becomes smaller. Therefore,
By setting the pressure-receiving areas of the diaphragm 15 and the valve body 13 appropriately and keeping the spring force of the return spring 18 relatively small, when the main intake passage 6a is throttled by the intake throttle valve 7, combustion is prevented. The valve body 13 is opened during the intake stroke when the negative pressure generated in the chamber 3 and the downstream side of the auxiliary intake passage 6b communicating therewith exceeds a predetermined value, and conversely, the valve body 13 is opened when the negative pressure becomes sufficiently small. is closed. On the other hand, when the intake throttle valve 7 is open, almost no intake negative pressure is generated, so the operation of the on-off valve 10 is stopped and the valve is kept completely closed. Note that the valve seat 12 is formed of a damping steel plate or plastic, and the surge tank 9 is
If a sound absorbing material is attached to the inner surface of the opening/closing valve 10, noise during operation of the on-off valve 10 can be reduced.

An intake throttle valve 7 provided in the main intake passage 6a is connected to an actuator 21. This actuator 2
1 is formed, for example, by a diaphragm device, and the passage 22
It is connected to the vacuum pump 23 via the passage 2.
A switching valve 24 is provided in the actuator 21 to switch between a state in which negative pressure is introduced from the vacuum pump 23 and a state in which atmospheric air is introduced into the actuator 21. And actuator 2
When atmospheric pressure is introduced into the vacuum pump 1, the intake throttle valve 7 is closed to a small opening, and when negative pressure is introduced from the vacuum pump 23, the intake throttle valve 7 is opened. These actuator 21, passage 22, vacuum pump 23 and switching valve 24 throttle the main intake passage 6a and
1 valve 10 operating state and main intake passage 6
A driving means is configured that can be switched to an operation stop state in which the operation function of the on-off valve 10 is stopped by opening the on-off valve 10.

Further, the intake throttle valve 7 does not close to the main intake passage 6 even in the closed state.
A is not completely sealed, but some intake air is allowed to leak into the combustion chamber 3.The reason for this is that the intake air temperature rises due to adiabatic expansion before the on-off valve 10 is opened during the intake stroke. This is to prevent the temperature from decreasing.

In addition, in extremely low speed ranges such as during cranking, the leakage rate from around the piston rings increases and the accuracy of the operating timing of the on-off valve 10 decreases, so the valve shaft of the intake throttle valve 7 is offset from the center. The leakage rate around the intake throttle valve 7 may be reduced by increasing the adhesion between the inner wall of the main intake passage 6a and the intake throttle valve 7.

Reference numeral 25 denotes a control circuit (control means) for controlling the drive means, which is composed of a microcomputer or the like, and controls the actuator 21 with a control signal output to the switching valve 24 to introduce intake air through the drive means. The regulation device is controlled so that, during acceleration, the operation is stopped and the regulation of intake air intake is released. In this embodiment, the on-off valve 10 is operated in the starting operation region and the operating region where HC etc. are inherently likely to occur, and the operating function of the n-close valve 10 is stopped in other operating regions. In the operating range in which the on-off valve 10 is operated, the operation flAbX in which the valve 10 is operated is corrected according to fluctuations related to the combustion temperature of the engine such as cooling water temperature, intake air temperature, intake pressure, exhaust temperature, etc. Even if it is, it will be 171 when accelerating.
The operating function of the 1w1 valve 10 is stopped.

In order to perform such &1jill, the control circuit 25
is a rotation speed detection means 26 installed in a fuel injection pump, etc.
and a signal that detects the operating state from the load detection means 27, etc., a detection signal from the water temperature sensor 28 that detects, for example, the cooling water temperature as a variation related to the combustion temperature of the engine, and a change in the lever position of the fuel injection pump. A detection signal from an acceleration detection means 29 that detects acceleration by detection or the like is input.

In the control circuit 25, as shown in FIG. 4, an on-off valve operating range A in which the on-off valve 10 is operated regardless of the water temperature and a correction range VLB in which the on-off valve 10 is operated only when the water temperature is low are set in advance. ing. That is, the fourth
The figure shows the on-off valve operating range A, the correction range B, and the operation stop range C where the operating function of the on-off valve 10 is always stopped, with the horizontal axis representing the engine rotation speed N and the vertical axis representing the fuel injection 10 corresponding to the load. It shows. In this figure, Ll is the R-roaring fuel injection 61! during normal operation. Ii line, L2 is the fuel increase line at startup, Ls is the maximum speed line, L4 is the limit line of the on-off valve operation area A, and Ls is the limit line of the correction area B. As shown in this figure, the on-off valve operating region A is set to include a starting operation region and a comparatively low-speed, low-load operation region, and the above-mentioned correction region B is set to include a starting operation region and a relatively low-speed, low-load operation region. This is an area where HC etc. are likely to occur sometimes,
The limit line L5 is the limit line L of the on-off valve operating area A.
It is set to a certain degree higher rotation side than 4. The operation stop region C is located on the high-speed, high-load side of the limit line L5.

FIG. 5 shows 1, II m 171 by the control circuit 25.
As shown in this figure, the control circuit 25 detects the engine speed and the load in step S1. S2), based on these detection signals, it is checked whether the on-off valve is in the above-mentioned on-off valve operating range A (step 83). When the on-off valve is in the operating region, it is checked based on the acceleration detection whether or not it is accelerating (step 84, Ss), and when it is not accelerating, the intake throttle valve 7 is closed to a small opening. state, the on-off valve 10 is operated (step S6), and during acceleration, the intake throttle valve 7 is opened to open the main intake passage 6a, thereby stopping the operating function of the on-off valve 10 (step S6).
7).

If it is not in the on-off valve operating region, it is checked whether it is in correction region B (step S8), and if it is in correction region B, it is determined whether the water temperature is below a predetermined temperature (for example, 50 degrees Celsius) based on the water temperature correction signal. Find out. Even when the water temperature is in the correction region B and the water temperature is below the predetermined temperature, the on-off valve 10 is operated through step Sa and step $5 except during acceleration;
Stop the operating function of 0. When the water temperature is in the correction region B and is higher than the predetermined water temperature, and when it is not in either the on-off valve operation region A or the correction region B, the process moves to step $7. The operating function of the closing valve 10 is stopped.

According to the above-described intake system, when the operating state is in the on-off valve operating region A, or when the water temperature is in the correction region B and the water temperature is below a predetermined value, the main intake is controlled by the intake throttle valve 7 except during acceleration. The passage 6a is narrowed and the on-off valve 10 is operated to open in the middle of the intake stroke. As a result, the introduction of intake air into the combustion chamber 3 is restricted until the middle of the intake stroke, and a large amount of intake air is suddenly introduced into the combustion chamber 3 from the middle of the intake stroke, and the temperature inside the combustion chamber 3 increases due to adiabatic compression of the intake air. do.

At this time, even if the charging temperature decreases somewhat due to restrictions on intake air introduction, the combustion temperature is sufficiently raised due to the adiabatic compression described above, and in operating conditions with a large excess air ratio, the intake air R is insufficient relative to the fuel. In this way, ignitability and combustibility are improved, and HC etc. are reduced.

Also, during acceleration, the intake throttle valve 7 is opened and the main intake passage 6a is opened.
By opening, the restriction on intake air introduction is lifted, and intake air is freely introduced into the combustion chamber 3 from the main intake passage 6a throughout the entire intake stroke.

Therefore, even if the amount of fuel is increased during acceleration, insufficient air intake will not occur, and smoke generation and deterioration of acceleration performance can be prevented.

Furthermore, in this embodiment, even when the operating state is in the correction region B and the water temperature is higher than the predetermined value, or when it is in the operation stop region C, combustion is originally performed well and the HC
Since such occurrences are rare, the operating function of the on-off valve 10 is stopped to remove the restriction on intake air introduction, thereby reducing the pumping loss and preventing the occurrence of smoke during high rotations and high loads.

In the above embodiment, the restriction on intake air introduction is completely released during acceleration, but the restriction on intake air introduction may be relaxed to some extent by opening the intake throttle valve 7 by a predetermined opening degree.

Further, the specific structure of the intake air introduction M control device and the driving means in the present invention can be changed in various ways, and some examples will be explained below.

In the second embodiment shown in FIGS. 6 and 7, an automatic valve type on-off valve 10 is provided in the main intake passage 6a, and no sub-intake passage 6b is provided.

This on-off valve 10 has a structure similar to that of the first embodiment and is configured to close the WU in response to pressure changes, but its end is attached to the main intake passage 6a via a rotating shaft 10a. As a result, it can be rotated between a state where it is located in the main intake passage 6a and a state where it is housed in a recess 30 provided in the side wall of the main intake passage 6a. When the on-off valve 10 is rotated to the retracted position, the main intake passage 6a opens and the on-off valve 10 stops operating. 31, a passage 32 for operating the same, a vacuum pump 33, a switching valve 34, etc. constitute a driving means. Further, a small-diameter leak passage 6 is provided between the upstream side and the downstream side of the on-off valve 10 of the main intake passage 6a.
A check valve 35 is provided in the leak passage 6G to prevent the filling rate from decreasing due to backflow of intake air.

Even with the device of this embodiment, when the on-off valve 10 is located in the main intake passage 6a, only a small amount of intake air is introduced from the leak passage 6C until the middle of the intake stroke, so that the inside of the combustion chamber 3 and The pressure on the downstream side of the main intake passage 6a that communicates with the main intake passage 6a gradually decreases, and in response to this pressure decrease, the on-off valve 10 opens during the intake stroke, and thereafter intake air is suddenly introduced and adiabatic compression is performed. As a result, the intake air temperature increases. Further, when the WU closing valve 10 is rotated to the retracted position, the operation of the opening/closing valve 10 is stopped and the main intake passage 6a is opened, resulting in an inoperative state.

Then, the control circuit 25 operates the drive device 1i111I based on the area settings as shown in FIG. By letting
The same functions and effects as in the embodiment can be obtained.

FIG. 8 shows a third embodiment of the device of the present invention. In this embodiment, an intake throttle valve 7 is provided in the main intake passage 6a as an intake air introduction jJI Ill i 21, while an intake throttle valve 7 is provided in the auxiliary intake passage 6b. An on-off valve 40 made of a rotary valve that rotates in conjunction with a shaft (not shown) is provided. An interlocking mechanism between this n-closing valve 40 and the engine output shaft (
(not shown), the opening/closing timing of the on-off valve 40 is set so that the n-close valve 40 opens during the intake stroke.

Also in this embodiment, when the main intake passage 6a is throttled by the intake throttle valve 7, the introduction of intake air is regulated by the operation of the n-closing valve 40, and adiabatic compression of the intake air is performed. Also,
When the intake throttle valve 7 is opened, intake air is freely introduced from the main intake passage 6a into the combustion chamber 3, so even if the on-off valve 10 is rotating, the restriction on intake air introduction is lifted, and the on-off valve 1 is substantially
0 operating function is deactivated. Therefore, in this case as well, it is sufficient to provide the same driving means as in the first embodiment for the intake throttle valve 7 and to control the driving means by the control circuit 25 in the same manner as in the first embodiment.

Further, by providing a means for interrupting the interlocking mechanism between the 1FIW1 valve 10 and the engine output shaft, the rotation of the on-off valve 10 itself is stopped when the intake throttle valve 7 is opened. You can do it like this.

As another embodiment, an intake passage configuration consisting of a main intake passage and a leak passage as shown in the second embodiment, and a rotary valve type on-off valve that opens in the middle of the intake stroke in conjunction with the engine output shaft is used as the main intake passage. It may also be provided in the intake passage. In this case, by incorporating into the interlocking mechanism a movement blocking means that can stop the F11 closing valve in the open state or an opening/closing timing variable means that can change the opening/closing timing of the opening/closing valve, the intake air introduction regulation Ill can be canceled. or loosening, and such means may be controlled by a control circuit.

(Effects of the Invention) As described above, the present invention includes an intake air introduction regulating device that opens the on-off valve provided in the intake passage in the middle of the intake stroke to perform adiabatic compression of the intake air, and also provides for steady operation with a large excess air ratio. During acceleration, the above-mentioned on-off valve is operated, and during acceleration, the control is performed in such a direction that the restriction on intake air intake due to the operation of the above-mentioned on-off valve is released, so that the HC in the exhaust gas is It is possible to prevent insufficient air intake from occurring during acceleration when the amount of fuel is increased, and to prevent the occurrence of smoke during acceleration and deterioration of acceleration performance while reducing the above as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a device according to a first embodiment of the present invention, and FIG.
The figure is a vertical side view of this device, Figure 3 is an enlarged sectional view of the on-off valve, Figure 4 is an explanatory diagram showing the on-off valve operation area and operation stop area, Figure 5 is a control flowchart, and Figure 6 is an 2
FIG. 7 is a cross-sectional view taken along line 1--2 in FIG. 6, and FIG. 8 is a vertical side view showing the third embodiment. 1... Cylinder, 3... Combustion chamber, 4... Intake valve,
6... Intake passage, 7... Intake throttle valve, 10... On-off valve, 40... On-off valve, 21.31... Actuator, 25... Control circuit, 29... Acceleration detection means. Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. An on-off valve is provided in the intake passage, and the on-off valve is closed until the middle of the intake stroke to restrict the introduction of intake air into the combustion chamber.
In an intake system for a diesel engine equipped with an intake air introduction regulating device that rapidly introduces intake air into a combustion chamber to perform adiabatic compression by opening the on-off valve during the intake stroke,
an acceleration detection means for detecting an acceleration state of the engine; and a control means for controlling the intake air introduction regulating device in a direction to release the regulation of intake air introduction by the operation of the on-off valve during acceleration according to the output of the acceleration detection means. An intake system for a diesel engine characterized by the following: